Abrasive tool



Nov. 12, 1946. A. FIELD 2,410,870

ABRAS IVE TOOL Filed Aug. 7, 1944 INVENTOR ALBERT FIELD ATTORN EYS Patented Nov. E2, 1946 um'reo STATES PATENT OFFICE ABRASIVE TOOL Albert Field, Dayton, Ohio Application August 7, 1944, Serial No. 548,367 (or. 51-185) I 2 Claims. 1

The present invention relates to abrasive tools employed for polishing or finishing metal, rubher and plastic materials and an abrasive element for use in connection with such tools, also an improved method for making such elements.

In my Patent, No. 2,290,098, granted July 14, 1942, there is disclosed an improved form of abrasive tool in which the abrasive element comprises a strip of abrasive material such as emery cloth having an adhesive along one edge of the material and wound to a cylindrical shape, with each layer in close contact with the under layer so as to constitute an abrading element of solid and integral character. The bond between the adjacent layers is strengthened by breaking down the abrasive surface at predetermined points-in order to provide an area which can be brought into more close adhesive engagement with the layer on which it rests and thereby increase the rigidity of the convolutions as a whole. The adherence between these superimposed layers is to prevent the rolled portions from becoming loose in use. The strip is rolled on a slotted mandrel and as the glue hardens the forming mandrel is removed so that the opening left in the cylindrical member is adapted to receive a work shaft or arbor.

In operation, the shaft is inserted in a revolving power head such as a drill chuck and the work piece is brought into contact with the abrasive surface of the element which has the efiect of smoothing the surfaces by abrasion.

As the art developed, it was found desirable to employ abrasive elements of shapes other than cylindrical in order to accommodate the multitudinous numberof shapes of work pieces. An abrading tool having a conical configuration was found to be highly useful in this connection and the problem presented itself as to the best way such an element could be practically made in view of its taper. The present invention is concerned with an improved method of fabricating abrasive tools of this type, i. e. of conical shape, and also an improvement in an abrasive tool made according to the improved process.

The primary object of the invention is to provide a tool of the character described which shall have a long tapering configuration and which can be readily fabricated by machine or hand and in which the various convolutions are rigidly held together so as to impart long life to the abrasive tool as a whole.

Another object is to provide a tool of the abrasive strip type which requires the minimum abrasive strip material to form the tool and also a reduced amount of adhesive without sacrificing the effectiveness of the finished roll. Thus the cost of manufacture of the improved product made in accordance with the method described hereinafter is materially reduced.

The invention will be better understood when reference is made to the following description and accompanying drawing in which:

Figure 1 represents an elevational view of a complete, abrasive tool including the shaft or shank and the abrasive elementmade in accordance with the present invention.

Figure 2 is an elevational view of the'shank or shaft removed from the abrasive element to show the manner in which the shank is rigidly secured to the element.

Figure 3 is an enlarged perspective view of the abrasive element partially unwound to indicate the method of manufacture.

Figure 4 is a development of the abrasive element in unrolled form to show the shape of the piece of abrasive material.

Figure 5 is a perspective view of the slotted mandrel on which the abrasive strip or piece is wound to form the working end of the abrasive tool.

Referring to Figures 1 and 2, reference character I designates the shaft or shank of the abrasive tool, the shank being adapted to be received at its upper end in a drill chuck or power driven clamping head in order to rotate the shank. The lower end of the latter as indicated at 2 is tapered and terminates in a portion 3 having a coarse thread which is separated from the upper portion I by a shoulder 4. The abrasive portion or element of the combined tool comprises a conically shaped piece 5 of abrasive material which is formed by mning method and in which the strip has'ja fairly steep angle of incline indicated at 6. v The upper portions of the rolled edge 6 is provided on its interior or abutting surfaces with an adhesive constituted of any strong glue suited to the character of the surface of the abrasive element. It will be understood that the latter is usually formed of emery cloth although in certain instances sandpaper may be employed so that the outer surface of the stripis of a coarse abrasive character and the underneath surface is fairly smooth. The glue is preferably applied to the smooth surface.

When the abrasive strip has been wound in a manner described hereinafter and the adhesive allowed to set, a tapered hole will have been left within the conical member. The upper edge will have been so strongly bonded as to permit the threads 3 of the shank I to firmly bite into the element and therefore securely held thereon. It is apparent that after continuous use the abrasive surface may wear smooth, necessitating discarding the element 5, in which case it is simply necessary to unscrew the shank at the threads 3 and to apply a new abrasive cone. The fact that the lower end of the cone contains no adhesive between turns tends to impart to this end a certain amount of yieldability or resiliency and therefore eliminates any tendency to gouge or to mar the work under certain conditions which is a characteristic of less flexible abrading tools.

In the manufacture of the abrasive element, the first step is to provide the strip of abrasive material. It had been customary heretofore to utilize a strip having parallel edges so that as the strip was wound conical or helical fashion the uppermost edge of the strip would extend considerably beyond the shoulder I in which case it became necessary to cut or shear the material in excess at this position. This was a difficult Job as obviously the presence of the abrasive particles would dull the cutting instrument and in addition there would be considerable waste of material. However, in accordance with the present invention, I propose to start out with a strip which is of such predetermined shape considering the inclination or angle of taper desired and the length of the tapered tool 2 as to cause the upper edges of the top rolls or turns to coincide with one another to constitute a squared fiat end.

The starting strip of material is shown in Figure 4 and it will be noted that the strip is provided with two edges a, b, substantially at right angles to one another, the edge a being considerably greater in length than the edge b. The outer edge e is cut to a shape of varying curvature, that portion of the edge near the edge b being somewhat more fiat than the edge which subjoins the edge a. The exact shape of the edge e can be determined by cutting the edges square at the shoulder l and then unwinding the roll or may be predetermined in any other manner. Succeeding strips can then be cut to the same shape for use in connection with similar shanks and tapered portions.

In fabricating the abrasive element, assuming that the strip has been cut to a predetermined :rj 2 either calculated or found by experiment, the edge b of the strip is inserted within a slot 1 extending longitudinally of a manufacturer's mandrel 8. The latter is then turned as indicated in Figure 5 while exerting a pull on the strip. An area 9 on the smooth or unabrasive side of the strip is coated with a good adhesive, either while the strip is in flat form as indicated in Figure 4, or during the rolling or winding process as shown in Figure 5. It will be noted that this area extends over only a portion of the outer edge e of the strip as it is necessary to bond only the last few remaining layers of the conically shaped element in order that all of the turns shall remain in a fixedly secured condition. As the winding proceeds, each portion of the upper edge 0 of the strip will rest on every other portion throughout its entire length and will form a sharply defined shoulder or end on the abrasive element so that when the entire strip is wound on the mandrel a solid and rigid cone of abrasive material is formed which compares favorably in operation with a wheel or a rod formed of grindstone material. The slot 1 ex- 4 tends to the lower end of the mandrel 8 so that in order to remove the finished cone from the mandrel it is necessary merely to slip the strip downwardly out of the slot.

It will be noted in Figure 5 that the lower edge a takes an inclined position with respect to the horizontal direction as the winding proceeds and as shown in Figures 1 and 3 its angle of inclinationbecomes fairly steep. The advantage of this particular construction is that there is only a limited number of layers of material at the lower end of the cone where maximum yieldability is required but there is the maximum number of layers at the upper end of the cone where a bearing surface is necessary in order to receive the threaded portion of the shaft or shank I.

My invention contemplates the use of a strip 5 of abrasive material as shown in Figure 4 of a predetermined shape and size such that when the strip is wound on a mandrel 8 the convolutions at the upper or'larger end of the cone will form a square end, thus eliminating the necessity for any cutting of excess material after the winding operation has been completed. The direct result of this improvement is that for a given piece of abrasive material, such as emery cloth, more patterns 5 can be cut from stock than was heretofore possible since the size of the strip 5 is reduced to a minimum and there is no excess material. It is apparent that my invention is not limited to a strip in which the glue is applied to any particular area 9 but if desired an adhesive can be applied to any part of the strip although in the interest of economy I have found it necessary to limit the area and position of the glued portion.

The edge e could, if desired, be perforated in any suitable manner by causing a perforating device to act upon the strip 5 in such a manner that the device enters the strip by first engaging the abrasive surface thereof and then passing through the fabric, in the case of emery cloth. to cause said material to break out from the surface and leave protrusions (not shown) which in effect roughens the surface around the protru slons. Adhesive may be applied to areas about these protrusions to cause closer adhesive engagement at these positions with the underlying surfaces as the strip is being rolled into a conical formation. Thus the invention contemplates any and all ways and methods of securing the turns together provided that the initial strip or strips takes on a shape such that when rolled into the conical formation the upper portion shall present a square shape and will not require any severing of excess strip material.

While the structural arrangement of the apparatus disclosed and described herein constitutes a preferred form of the invention, it is to be understood that the apparatus is capable of alteration without departing from the spirit of the invent-ion, and that all modifications that fall within the scope of the appended claims are intended to be included herein.

Having thus fully set forth and described my invention what I claim as new and desire to secure by Letters Patent is:

1. A device of the class described comprising in combination a frusto conical mandrel and an abrasive element comprising a spirally rolled strip of material having abrasive applied to one surface thereof, the material being rolled in a frusto conical form and in unrolled condition being bounded by a pair of angularly disposed straight edges which are subtended by a curvilinear edge, with adhesive applied along said curvilinear edge on the opposite side from said abrasive material, said frusto conical mandrel having a slot and said strip being wound around the frusto conical mandrel with one of its edges disposed in said slot and another edge presenting a steep spiral along the face of the abrasive surface of the wound frusto conical element.

2. A device of the class described comprising in combination a frusto conical mandrel and an abrasive element comprising a spirally rolled strip of material having abrasive applied to one surface thereof, the material being rolled in a frusto 6 conical form and in unrolled condition being bounded by a pair of angularly disposed straight edges which are subtended by a curvilinear edge, said straight edges forming a substantially right angle, with adhesive applied along said curvilinear edge on the opposite side from said abrasive material, said frusto conical mandrel having a slot and said strip being wound around the frusto conical mandrel with one of its edges disposed in said slot and another edge presenting a steep spiral along the face of the abrasive surface of the wound frusto conical element.

ALBERT FIELD.- 

